Pharmacognosy Tyler, Varro E.; Brady, Lynn R.; Robbers, James E.

Steroids

Steroids constitute a nar_r*_
class of compounds that is wide ■ -ascrir-
uted throughout nature. The drsersr. of
biologic activities of steroids dae

development and control at ~~ - rtcr.ca;-
tive tract in humans lestradioi. rrcsssaer-
one, testosterone), the rr.o:“ £ :c tracts
(ecdysone), and the indataor -t ^ « ■ ae-
production in aquatic tung •.

In addition, steroids con:r£*s3e h * '*Tde
range of therapeutic apphcaUons s-«cr as
cardiotonics (cfigrtoxin. rt i " D precsr-
sors (ergosterol), oral contracepr-** worses
(semisynthetic estrogens and prc*crscr>-
anti-inflammatory agents looncsa T »' 't
and anaboHc agents (androcens

NOMENCLATURE

A steroid is any corepoared that contains
a cyclopentanoprfnvdTophenaj'-ihiene t.jt
cleus. The chemical nomenclature of ste-
roids is based on this fundteMbl carbo-
cycle with adjacent side-chain carbon
atoms. Each parent tetracyclic hydrocarbon
bears a specific stem name, and some of
the principal hydrocarbons are shown in
Figure 7—1. Steroids are numbered and
rings are lettered as indicated in the struc-
tural formula for cholesterol. If one or more
of the carbon atoms shown in the structure
of cholesterol is not present, the number-
ing of the remainder is undisturbed.

Cholesterol

When the rings of a steroid are denoted
as projections onto the plane of the paper,
an atom or group attached to a ring is
aexmed a (alpha) if it lies below the plane
of the paper or {3 (beta) if it lies above the
of the papier. In formulas, bonds to
m i i or groups attached in an a config-
aca fcion are shown as broken lines, and
Wk to atoms or groups attached in a 0
configuration are shown as solid lines.

The use of a steroid stem name implies
that atoms or groups attached at the ring-
janction positions 8, 9, 10, 13, and 14 are
orie n ted as shown in Figure 7-2 (80, 9a,
100 130, 14a), and a carbon chain (R) at-
tacfwd to position 17 is assumed to be
S-onented The configuration of hydrogen
or a scbsctuent at the ring-junction posi-
tion 5 is always designated by adding a or
0 after the numeral 5. This numeral and
w*»r are placed immediately before the
ste m name The implication of these con-
ventions of nomenclature is that, in most
steroids nngs B and C and rings C and D
are fused rrans, whereas rings A and B may
be fused either cis or trans. For example,
the bile acid, cholic acid, has a cis-fused A/

steroids

157

Ergostane

Stigmastane

Bufanolide

Fig. 7-1. Principal steroid stereoparent hydrocarbons.

158

STEROIDS

Fig. 7-2. Orientation of steroid substituents.

A/B ring junction. The chemical name of
cholic acid is 3a, 7a, 12a-trihydroxy-5p-
cholan-24-oic acid. The sex hormone an-
drosterone, chemical name 3a-hydroxy-5a-
androstan-17-one, has a frans-fused A/B
ring junction.

Androsterone

BIOSYNTHESIS

Steroids are formed biosynthetically
from isopentenyl pyrophosphate (active is-
oprene) and involve the same sequence of
reactions as does terpenoid biosynthesis.
In fact, the triterpenoid squalene is an in-
termediate in steroid biosynthesis. Most
knowledge of the biosynthesis of steroids
has been derived from studies of choles-
terol production. Although this compound
is not necessarily a direct precursor of all
other steroids, its formation may be con-
sidered as a general mechanism of steroid
biosynthesis. The familiar acetate -*—*
mevalonate — > isopentenyl pyrophos-
phate ->— > squalene — » cholesterol path-
way is outlined in Figure 7-3.

The first step in the pathway by which
squalene is transformed into sterols is its
stereospecific conversion into S-squalene
2,3-epoxide by squalene epoxidase. In the
next step, the key enzyme involved in the
cyclization of squalene 2,3-epoxide to the
first cyclic sterol precursor in animals and
fungi is 2,3-oxidosqualene:lanosterol cy-
clase. Lanosterol is replaced in photosyn-
thetic organisms by its isomer cycloartenol,
and the enzyme involved is 2,3-oxido-
squalene: cycloartenol cyclase. The cycli-
zation reaction has been called one of the
most complicated in all of biochemistry. For
example, squalene is an acyclic molecule
with 6 double bonds, and the lanosterol
molecule has 4 rings and 7 asymmetric cen-
ters, all properly oriented. As shown in
Figure 7—3, a proton initiates the cycliza-
tion by attacking the epoxide bond. Each
of the rings forms successively, involving
attack by a tt bond on a specific carbon.
The reactions are fast enough and the in-
termediates rigid enough that stereochem-
istry is preserved as the rings form. Each
•rr-bond attack leaves behind a carbonium
ion, which is the target of the next attack.

After the rings are formed, the resulting
carbonium ion intermediate, which has a
positive charge at C-20, is stabilized by
rearrangements involving 2 hydride shifts
(17-»20, 13-*17) and 2 methyl shifts
(14— >13, 8— >14). These shifts result in the
migration of the positive charge to C-8 and,
with the loss of a proton from C-9, either
the 9,10,19-cyclopropane ring of cycloar-
tenol or the 8,9-double bond of lanosterol
may be formed. The conversion of the
compound, lanosterol, to the C 27 steroid,
cholesterol, involves the loss of 3 methyl
groups, the shift of a double bond, and a
reduction of a double bond. The sequence
in which these reactions take place may
vary, depending on the organism. Con-
sequently, numerous intermediates, in-
cluding zymosterol, have been isolated
that represent various stages in this trans-
formation.

ch;

0 0 op

CH COOH - CoA Al> CH-C-S-CoA <*, .c-s-co*, CH 3 C-CH 2 -C- S-CoA

A Cetate Acetyl-CoA AcetoacetylCoA

1 ?

ch k oh

CH k oh NADPH, unr . r r

HOOC C CH 2 0(P) HOOC .C. CH,OH < -*■ HOOC C

n ch/ x ch/

5-Phosphomevalonic

acid

[atp

CH K/

N / \ / 2

CH, CH :

Mevalonic acid

|CHj-C- S— CoA
0

■CoA

CH °H j,

\ . A s -

hooc x X / CH J-°IP?)
CH 2 CH ?

5-Pyrophospho-3-
phosphomevalonic acid

ATP

CH,

!

CHj CH 2

3lsopentenyl

pyrophosphate

.. CH 2 -0(PP)

// \ / 2

A-Hydroxy*/i*methylglutaryl-CoA

CH 3

A / ch -°@

ch 3 ch

3,3-Dimethylallyl

pyrophosphate

CH 3

i

K,

CH, V

ch 3

A.

CH,

.CH,.

, /-A. isopentenyl

:h 2 — o(pp) '

CH 3

CHj

c. ch 2 a

py ;:T ch/'ch' W ch

Farnesy! pyrophosphate

I NADHH ?

j Farnesyl pyrophosphate

ch 2 -o(pp)

Geranyl pyrophosphate

r

CH j .

''vV.

..CH

CH,

CH,

CH 3 i

1 %

fi

ch 3 [ ch,

A

ch, '"ch,

CH,

Squalene

CH -X

'V^

nx

N r A

h® 1 o:

'

Ar~

CH,

'CH,

CH,

.CH, ;

y

Oxidosqualene

CH,

LH,

3 A

HO

19 CHj | 9

anix i

10 \ J CH,

HO

CH/ 'CHj H ; i'

Carbonium *on intermediate

r'T

Ah'"

' CH 3

CH,

A -

CH 3

Cycloartenol

,.CH 3

CHj

..CH,

CH 3

CH,

CH,
I 1

"A

-J-

CHf CH 3

ch t

CH j i

i ^

Y A
>— j
Ch,

i j

CH,

lanestc/OJ

Yi% 7-3. v sir oi' cnoiesterul.

HO"

CH 3 .,

CH

CH

A

Cholesterol

^CHj

CH,

1 59

160

STEROIDS

STEROLS

The first steroids isolated from nature
were a series of C27-C29 alcohols that were
found in the lipid fractions of many tissues.
These compounds were solids and there-
fore named sterols from the Greek stereos,
meaning solid (Fig. 7 - 4 ). The most widely
occurring sterol is cholesterol. It was first
isolated from human gallstones and, be-
cause it is a constituent of animal cell mem-
branes, it has been found in all animal tis-
sue. It is one of the chief constituents of
lanolin and therefore is found in many
drug products. Until recently, cholesterol
was thought to be restricted to the animal
kingdom; however, it has now been iden-

tified in algae, fungi, actinomycetes, bac-
teria, ferns, and higher plants.

Much has been written about cholesterol
and human health. Cholesterol is present
in atherosclerotic plaques, and feeding of
cholesterol to susceptible animals has in-
duced atherosclerosis. In humans, ather-
osclerosis is frequently associated with
conditions in which the blood cholesterol
is elevated. However, at the present time,
the evidence of a causal relationship be-
tween cholesterol and atherosclerosis is
still indirect.

The principal sterol in fungi is ergosterol.
This C 28 sterol arises biosynthetically
through a transmethylation reaction of the
cholestane side chain involving S-adenosyl

7-Dehydrocholesterol
(Provitamin D 3 )
Cholesta-5,7-dien-3/^ol

28 9 H 3

Ergosterol
(Provitamin D 2 )
Ergosta-5,7,22-trien-3/^ol

Stigmasterol

Stigmasta-5,22-dien-3/^ol

/^-Sitosterol

Stigmast-5-en-3/^-ol

Fig. 7-4. Sterols.

STEROIDS

m

methionine. Ergosterol is also known as
provitamin D 2 because, upon ultraviolet ir-
radiation, a series of isomerizations with
the subsequent opening of ring B results
in the formation of vitamin D 2 . Vitamin D 3
is formed in the same manner from 7-de-
hydrocholesterol. This compound occurs
in small amounts with cholesterol in ani-
mal tissue, including human skin, where
irradiation from the sun catalyzes the for-
mation of vitamin D 3 . The vitamin D com-
pounds are discussed in the chapter on vi-
tamins.

The most common sterol in plants is
3-sitosterol (stigmast-5-en-3p-ol), a C„
compound. It has been shown that a sec-
ond transmethylation from methionine ac-
counts for the C-29 atom. In general, si-
tosterols are widely distributed throughout
the plant kingdom and may be obtained
from wheat germ oil, rye germ oil, corn oil,
cottonseed oil, and other seed oils.

Closely related to 3-sitosterol is the
sterol, stigmasterol, which was first iso-
lated from calabar beans but is also found
in soybean oil. The double bond at position

of stigmasterol allows it to be more read-
ily converted into the pregnane-type ste-
roid hormones than 3-sitosterol; conse-
quently, the extraction of stigmasterol from
soybean oil is an important commercial
process.

BILE ACIDS

In the liver of humans and other animals,
the side chain of cholesterol is degraded to
C 24 steroids, which possess a C-24 car-
boxyl. These steroids are collected in the
bile; therefore, they are referred to as the
bile acids (Fig. 7-5). The primary bile acids
formed in the human liver are cholic acid
and chenodesoxycholic acid. Desoxycholic
acid and lithocholic acid are also found in
substantial amounts in mammalian bile;
however, they are not formed in the liver.
They are produced in the intestinal tract by
the action of microorganisms on cholic acid
to form desoxycholic acid and on cheno-

desoxycholic acid to form lithocholic acid.
Their presence in the bile is attributed to
enterohepatic circulation. Generally, the
bile acids do not exist in the free state but
are conjugated through a peptide bond to
either glycine or taurine (Fig. 7-6). The
conjugated bile acids are discharged into
the duodenum where they act as emulsi-
fy* 1 ^ agents to aid in the intestinal absorp-
tion of fat. Bile salts are the sodium salts
of the conjugated acids and are the prin-
cipal constituents of ox bile extract. It is
usually given in a dose of 300 to 600 mg
daily. After absorption, the bile acids ex-
hibit choleretic action by increasing bile
flow. They also have a mild laxative effect,
and since there is no evidence of efficacy
in replacement therapy for bile deficien-
cies, the principal use of ox bile extract is
as a laxative.

Ox bile extract is prepared by partial
evaporation of fresh ox bile, precipitation
of the mucus and albuminous matter with
alcohol, filtering, washing, and evapora-
ting the combined filtrates to dryness at a
temperature not exceeding 80° C. It con-
tains an amount of the sodium salts of gly-
cocholic acid and taurocholic acid equiva-
lent to not less than 45% of cholic acid.

NONPRESCRIPTION PRODUCT. Bilron Pul-
vules®.

Chenodiol (chenodesoxycholic acid)

suppresses hepatic synthesis of both cho-
lesterol and cholic acid, gradually replacing
the cholic acid and its metabolite, desox-
ycholic acid, in an expanded bile acid pool.
This contributes to biliary cholesterol de-
saturation and gradual dissolution of ra-
diolucent cholesterol gallstones. Chenodiol
has no effect on radiopaque (calcified) gall-
stones or on bile pigment gallstones.

The recommended dosage of chenodiol
is 13 to 16 mg/kg/day, divided into 2 doses.
The duration of treatment may be 2 years
or more. In addition, stones may recur
when therapy is discontinued. Because
there is a high incidence of adverse effects,
such as elevated liver enzyme levels and a
dose-related diarrhea, this agent is rec-

STEROIDS

162

Chenodesoxycholic Acid
3n,7n-Dihydroxy-5/^cholan-24-oic acid

Cholic Acid

3a ,7a , 12a -Trihydroxy-5/?-
cholan-24-otc acid

Desoxycholic Acid

3a , 12a -Dihydroxy-5/?-cholan-
24-oic acid

7m deoxygenation
by intestinal
microflora

CH

HO"

. J

H,C

ch ]

L

^COOH

Lithocholic Acid

3a -Hydroxy-5/? -cholan*24-oic acid

Fig. 7-5. Bile acids.

HjC .

? h chV

.A., I

0 o

,i H

C-N-CH^C 0 Na-

cnJ j

rfy

wcr^s^

^ OH

Sodium Glycocholate

0

HjC

SC

0

, H t

jC — N — CH ? — CH 2 — 0 — $ 0 Na*

&

' 'OH

Sodium Taurochotate

Fig. 7-6. Conjugated bile adds.

ommended only in patients who are poor
surgical risks for a cholecystectomy.

CARDIAC GLYCOSIDES

Some steroids present in nature are char-
acterized by the highly specific and pow-
erful action that they exert on the cardiac
muscle. These steroids occur as glycosides
with sugars attached at the 3-position of
the steroid nucleus. Because of their action
on the heart muscle, they are named car-
diac glycosides (Fig. 7-7). The steroid agly-
cones or genins are of 2 types: a carden-
olide or a bufadienolide. The more
prevalent in nature are the cardenolides,
which are C 23 steroids that have as a 17p
side chain an a,(3-unsaturated 5-membered
lactone ring. The bufadienolides are C 2 4
homologs of the cardenolides and carry a
doubly unsaturated 6-membered lactone

STEROIDS

163

Digitoxigenin

3/»,14-dihydroxy-5/3 > ,14/y-card-20(22)-enolide

Digoxigenin

3/i, 12/i, 1 4-trihydroxy-5/i, 1 4/>-card-20(22) enolide

Gitoxigenin R - H
3 / 1 , 14, 16/?-tri hydroxy-5/?, 14/i-card*
20(22)-enolide
Gitaloxigenin R = CHO
16/?-formyloxy*3/?, 14-dihydroxy-
5/3, 14/> , -card-20(22)-enolide

Ouabagenin

l/?,3/?,5, 1 1<*, 14, 19-hexahydroxy-5/>\14/?-card
20(22)-enolide

Scillarenin A

3/i, 14-dihydroxy- 14/? bufa-4, 20 , 22 *

trienolide

Fig. 7—7. Structural formulas of several aglycones of cardiac glycosides.

ring at the 17-position. The bufadienolides
derive their name from the generic name
for the toad, Bufo (the prototype compound
bufalin was isolated from the skin of
toads). An unusual aspect of the chemistry
of both cardenolides and bufadienolides is
that the C/D ring junction has the ris-con-
figuration. To obtain optimum cardiac ac-
tivity, the aglycone should possess an a,0
unsaturated lactone ring that is attached 0
at the 17-position of the steroid nucleus
and the A/B and C/D ring junctions should
have the as- configuration. Metabolic re-
duction of the double bond in the lactone
ring of digoxin to form dihydrodigoxin
may explain why certain individuals are
refractory to digoxin therapy. If the gly-

coside is cleaved, the aglycone retains car-
diac activity; however, the sugar portion of
the glycoside confers on the molecule sol-
ubility properties important in its absorp-
tion and distribution in the body. Oxygen
substitution on the steroid nucleus also in-
fluences the distribution and metabolism
of glycosides. In general, the more hydroxy
groups on the molecule, the more rapid the
onset of action and the subsequent dissi-
pation from the body.

The use of the cardiac glycosides in ther-
apeutics stems from the ability of these
compounds to increase the force of systolic
contraction. An increase in contractility in
the failing heart results in a more complete
emptying of the ventricle and a shortening

m

STEROIDS

in the length of systole. Thus, the heart
has more time to rest between contrac-
tions. As the myocardium recovers as a re-
sult of increased cardiac output and cir-
culation, the heart rate is decreased
through a reflex vagal effect. In addition,
the improved circulation tends to improve
renal secretion, which relieves the edema
often associated with heart failure.

In the use of cardiac glycosides to treat
congestive heart failure, the patient is
given an initial loading dose of the drug in
order to bring the heart under the influence
of the drug. Because the amount required
varies with the patient and the drug used,
the preparation is given in divided doses
while titrating the dose against signs of im-
provement. The patient is usually main-
tained indefinitely after the loading dose
by administering a daily maintenance dose
that replaces the amount of drug that is
metabolized and excreted. In toxic concen-
trations, the glycosides may increase car-
diac automaticity and lead to ectopic tach-
yarrhythmia. Ventricular extrasystoles are
the most frequent effect. With all the gly-
cosides, the therapeutic level appears to be
approximately 50 to 60% of the toxic dose.
This finding explains why dosage must be
carefully determined experimentally for
each patient.

Despite numerous experimental inves-
tigations, the mechanism of action of the
cardiac glycosides is still not completely
known; however, observations have im-
plicated Na v , K + -ATPase as the receptor
enzyme. This enzyme catalyzes the active
transport of Na+ out of the cell and the
subsequent transport of K + into the cell.

Na + , K + -ATPase operates in all cell
membranes to maintain the unequal dis-
tribution of Na f and K> ions across the
membrane. However, in the myocardium
the ion exchange is rapid because it is re-
quired after each heart beat; therefore, an
inhibition of Na + , lO-ATPase has a greater
effect on heart tissue than on other, cells of
the body. When the *eart beats, a wave of
depolarization passes trough it, changing

the permeability of the cell membranes.
Na + moves into the cell by passive diffu-
sion and K+ moves out. Na + , K"-ATPase
supplies the energy from ATP to reverse
this process and to pump the Na 4 * out of
the cell and the K 4 into the cell against a
concentration gradient.

Inhibition of Na + , K + -ATPase by the car-
diac glycoside results in an increase in Na +
and a decrease in K + within the cell which,
in turn, stimulates a secondary Na + Ca + +
exchange mechanism that functions to re-
move intracellular Na with a subsequent
increase in intracellular Ca + + . The positive
inotropic action or muscle contraction en-
hancement of cardiac glycosides is me-
diated through the increase in Ca + + . Ca ** +
interacts with troponin which then,
through its action on tropomyosin, un-
masks the binding sites on actin that bind
myosin, allowing for the formation of the
contractile protein actomyosin (Fig. 7-8).

Drug Interactions. This postulated mecha-
nism implicating intracellular cation levels
explains the development of toxicity symp-
toms in patients with certain plasma-elec-
trolyte imbalances who receive cardiac gly-
coside therapy. Potassium depletion
increases the susceptibility to cardiac gly-
coside toxicity; therefore, patients on con-
comitant therapy with such potassium-
depleting drugs as thiazide diuretics and
corticosteroids with mineralocorticoid ac-
tivity may require potassium supplemen-
tation or a reduced dosage of cardiac gly-
cosides. Conversely, patients treated with
cardiac glycosides should not commence
the excessive ingestion of any product con-
taining absorbable calcium, e.g., milk, cal-
cium gluconate, and dibasic and tribasic
calcium phosphate. Also, such patients
should not be given parenteral calcium be-
cause hypercalcemia can potentiate the car-
diac effect.

Digitalis

Digitalis or foxglove is the dried leaf of
Digitalis purpurea Linn£ (Fam. Scrophular-
iaceae) (Fig. 7-9). Its potency is such that.

STEROIDS

165

Fig. 7-8. Schematic diagram showing the interaction of contractile protein during muscle contraction. A =
actin, M = myosin, TM = tropomyosin, T = troponin. In the relaxed muscle, tropomyosin masks the sites
on actin to which myosin binds through steric blockage. In the activated muscle, Ca" ' interacts with troponin,
which brings about a conformational change in tropomyosin, unmasking the actin-to-myosin binding sites
and allowing for the formation of actomyosin.

when assayed as directed, 100 mg are
equivalent to not less than 1 USP digitalis
unit (100 mg of the USP Digitalis Reference
Standard). When digitalis is prescribed, pow-
dered digitalis is to be dispensed.

Powdered digitalis is digitalis dried at a
temperature not exceeding 60° C, reduced
to a fine or a very fine powder, and ad-
justed, if necessary, to conform to the of-
ficial potency by admixture with sufficient
lactose, starch, exhausted marc of digitalis,
or w r ith a powdered digitalis that has either
a lower or a higher potency.

Digitalis is from the Latin digitus , mean-
ing finger, and refers to the finger-shaped
corolla, so named by Tragus in 1539; pur-
purea is Latin and refers to the purple color
of the flower. The plant is a biennial herb,
probably indigenous to central and south-
ern Europe and naturalized in various
parts of Europe and in the northern and
western United States and Canada.

Digitalis seems to have been used exter-
nally by the Welsh. Parkinson recom-
mended it in 1640, but its internal use was
not in vogue until its recommendation by
Withering in 1776. It is an important drug
and has been official in most pharmaco-
peias of the world since the 18th century.

The leaves of other Digitalis species, D.
dubia, D. ferruginea, D. grandiflora, D. lanata,
D. lutea, D. mertonensis , D. nervosa, D. sub-
alpina, and D. thapsi , also show the pres-
ence of cardiac glycosides.

CULTIVATION OF DIGITALIS. Until re-
cently, digitalis w^as cultivated in Pennsyl-
vania by the S. B. Penick Company. At
present, however, digitalis and the digi-
talis glycosides used in the U.S. are ob-
tained principally from England and Ger-
many. In Germany, D. purpurea seeds,
which have been developed through strain
selection to yield plants with maximum
drug potency and with resistance to plant
diseases, are sown in greenhouses in
March. From the middle of May until the
beginning of June, the young plants are
planted outside in relatively small plots (1
to 10 acres). The areas of cultivation are
centered around a commercial drying unit
for medicinal plants at a distance of not
more than 20 km. To ensure potency, the
leaves must be rapidly and gently dried at
50 to 60° C as soon as the plants are har-
vested. This procedure must be followed
because the leaf contains hydrolytic en-
zymes which, if not rapidly inactivated,

166

STEROIDS

Fig. 7-9. Specimen plant of Digitalis purpurea.

cleave the glycosidic linkages, thereby giv-
ing rise to the less active genins. Also ex-
cess heat may split off water from the ter-
tiary hydroxy group at position 14 of the
steroid nucleus, thereby forming the in-
active anhydro compound.

The annual crop is harvested from the
middle of September to the end of October.
The weight of a fresh plant ranges from
200 to 500 g. The yield per acre, depending
on the quality of the soil and the effort and
skill of the farmer, may vary from 2.5 to
5.5 tons fresh weight/acre, which corre-
sponds to approximately 0:6 to 1.4 tons dry
weight/acre.

The harvested crop utilizes only the first
year's leaves (Fig. 7-10), which develop as

a dense rosette. Some of the plants remain
undisturbed to permit development of the
flowering stalk during the second season.
These flowering stems are the source of
seeds for future use. With the exception of
the plants used for seed production, all
other plants are harvested; consequently,
fresh cultivation of young plants is begun
each year.

CONSTITUENTS. The drug contains a large
number of glycosides, of which the most
important from a medicinal viewpoint are
digitoxin, gitoxin, and gitaloxin. The total
concentration of these 3 glycosides varies
appreciably with the plant source and the
conditions of growth. Also, because all are
secondary glycosides derived by hydroly-

STEROIDS

167

Fig. 7-10. Mature digitalis leaves showing the prominent veins of the
wmgeu petiole.

dorsal and ventral

surfaces.

Note the

sis of some of the sugars from the primary
or parent glycosides occurring in the leaf,
their concentration depends on the man-
ner of treatment of the plant materia! fol-
lowing harvesting.. Careful experiments
have revealed that the secondary glycoside
content in the leaf is about 10 to 20% of the
primary glycoside concentration. Reported
total concentrations of digitoxin, gitoxin,
and gitaloxin range from 0.09% in a poor-
quality Spanish sample to 0.225% in a su-
perior Japanese leaf; the average concen-
tration approximates 0.16%.

Nearly 30 other glycosides have been
identified in the drug. The major glyco-
sides, in terms of concentration, include
purpurea glycoside A, purpurea glycoside
B, glucogitaloxin, glucodigitoxigenin-bis-

digitoxiside, glucogitaloxigenin-bis-digi-
toxiside, glucoevatromonoside, glucogito-
roside, glucoianadoxin, digitalinum
verum, glucoverodoxin, stropeside, and
verodoxin (see Table 7-1).

ASSAY. Digitalis and its preparations must
be assayed biologically to ensure their po-
tency, however, because the crystalline
glycosides are definite chemical entities,
they can be assayed chemically. A number
of test animals have been used in the past:
guinea pigs, frogs, and cats. The animal
now employed in the assay procedure is
the pigeon.

Standardization is determined by com-
parison of the effect of a known dilution of
the drug with that of a similar dilution of
the USP Digitalis Reference Standard.

STEROIDS

168

Table 7-1. Composition of the Principal Glycosides of Digitalis purpurea

Glycoside Sugars

Derivatives of Digitoxigenin

Purpurea glycoside A 3 digitoxose, 1 glucose

Digitoxin /;*$*.. 3 digitoxose

Gluco-digitoxigenin-bis-digitoxoside 2 digitoxose, 1 glucose

Gluco-evatronionoside 1 digitoxose, 1 glucose

Derivatives of Gitoxigenin

Purpurea glycoside B
Gitoxin

Gluco-gitoroside
Digitalinum verum
Stropeside

3 digitoxose, 1 glucose
3 digitoxose
1 digitoxose, 1 glucose
1 digitalose, 1 glucose
1 digitalose

Derivatives of Gitaloxigenin

Gluco-gitaloxin

Gitaloxin

Gluco-gitaloxigenin-bis-digitoxoside

Gluco-lanadoxin

Gluco-verodoxin

Verodoxin

3 digitoxose, 1 glucose
3 digitoxose
2 digitoxose, 1 glucose
1 digitoxose, 1 glucose
1 digitalose, 1 glucose
1 digitalose

Adult pigeons are anesthetized lightly with
ether, immobilized, and their alar vein is
exposed and cannulated. Definite volumes
of the diluted preparation are introduced
at 5-minute intervals until the pigeon dies
from cardiac arrest.

The bioassay of digitalis leaf can be crit-
icized because of the inability of the
method to predict oral potency of the drug.
For example, gitoxin in the leaf would con-
tribute to the intravenous assay potency,
but because it is poorly absorbed from the
gastrointestinal tract, it would not contrib-
ute significantly to the cardiac effect. This
observation assumes additional signifi-
cance when one considers that the amount
of gitoxin present in the leaf may vary
greatly, depending on the genetics of the
plant or the manner in which the drug is
harvested and prepared for market. As a
precautionary measure, care should be
taken to maintain patients on one brand of
digitalis tablets. This precaution decreases
the chances of dispensing a preparation
with an oral potency that is either reduced
or greater than that obtained by the patient
from a prior prescription.

In monitoring patient therapy with dig-

itoxin and digoxin, radioimmune assay
techniques have been developed that allow
for the measurement of nanogram quan-
tities of these glycosides in the blood
serum. The underlying principle is that
nonradioactive glycoside (in known stand-
ard solution or in patients' sera) will com-
pete with radioactively labeled glycoside
for combining sites on antidigitalis anti-
body. If one mixes varying quantities of
unlabeled glycoside with a standard
amount of radiolabeled glycoside, the
amount of radioactivity bound by a stan-
dard amount of antibody will decrease as
increasing amounts of unlabeled glycoside
are added. A standard curve can then be
constructed from which the concentration
of glycoside in a patient's blood serum can
be determined on the basis of the decrease
it causes in the binding of radioactive gly-
coside by specific antibody. Radiolabeled
glycosides and antisera are commercially
available. If stored properly, antibodies are
stable for many years, and 1 ml of anti-
serum may be employed in more than
100,000 determinations.

USES AND DOSE. Digitalis is used in the
form of tablets or capsules to treat conges-

STEROIDS

169

tive heart failure, paroxysmal atrial tachy-
cardia, atrial flutter, and atrial fibrillation.
See Table 7-2 for the usual dose of digitalis.
Dose must be reduced by 25 to 50% for the
elderly, for patients with lean body mass,
and for patients with metabolic or electro-
lyte disorders. The onset of action is 2 to 4
hours, and maximal effect occurs in 12 to
14 hours. Complete dissipation of the drug
from the body takes 2 to 3 weeks.

PRESCRIPTION PRODUCT. Digiglusin®
contains the products from the specially
prepared leaf of D. purpurea.

Digitoxin

Digitoxin is a cardiotonic glycoside ob-
tained from D. purpurea , D. lanata, and

other suitable species of Digitalis. On hy-
drolysis, digitoxin yields 1 molecule of dig-
itoxigenin and 3 of digitoxose. It is a highly
potent drug and should be handled with
exceptional care. Digitoxin occurs as a
white or pale buff, odorless, microcrystal-
line powder. It is a bitter substance that is
practically insoluble in water and slightly
soluble in alcohol. It is the most lipid-sol-
uble of the cardiac glycosides used in ther-
apeutics.

The major pharmacokinetic parameters
for digitoxin include complete oral absorp-
tion, which distinguishes it from other car-
diac glycosides. Upon oral administration,
the onset of action is 1 to 4 hours with a

Table 7-2. Dosage Schedules ol Various Forms of Digitalis and Cardiac Glycosides

Drug

Dosage

Form

Route of
Adminis-
tration

Usual Initial

Loading Dose

Usual

Maintenance

Dose

Digitalis

tablets or
capsules

oral

1.2 g divided in equal doses
administered every 6 hours

100 to 200 mg daily

Digitoxin

tablets

oral

rapid: 600 |jLg followed by 400
jxg, then 200 |xg at 4- to 6-hour
intervals

slow: 200 fig twice daily for

4 days

50 to 300 fig daily

injection

IV

same as rapid oral loading dose

100 to 200 fig daily

Digoxin

tablets

oral

rapid: 0.75 to 1.25 mg divided
into 2 or more doses, each ad-
ministered every 6 to 8 hours

slow: 125 to 500 jig daily for

7 days

125 lo 500 |ig daily

capsules

oral

rapid: 400 to 600 fig initially,
then 100 to 300 fig every 6 to 8
hours until desired effect is
clinically evident

slow: 50 to 350 |j.g daily divided
into 2 doses and repeated for

7 to 22 days as needed to
reach steady-state serum
concentrations

50 to 350 fig as 1 or
2 doses daily

injection

IV

400 to 600 fig with additional
doses of 100 to 300 fig every 4
to 8 hours

125 to 500 fig daily
in single or divided
doses

Deslanoside

injection

IV

IM

1.6 mg as a single dose or 800
fig initially and repeated every

4 hours

800 fig given at each of

2 separate injection sites

—

170

STEROIDS

peak at 8 to 14 hours. Approximately 50 to
70% of the glycoside is converted by the
liver to inactive genins, which are excreted
in the kidneys. Because of a long plasma
half-life (168 to 192 hours), it may take from
3 to 5 weeks for complete dissipation of the
drug from the body following discontin-
uation of therapy. It is estimated that a
drug-serum level of 14 to 26 ng/ml is re-
quired for full therapeutic effect, and levels
exceeding 35 ng/ml may produce symp-
toms of toxicity.

It has the same uses and precautions as
digitalis. The dose is given in Table 7-2.

PRESCRIPTION PRODUCT. Digitoxin is rep-
resented by Crystodigin®.

Digitalis Lanata

Digitalis lanata or Grecian foxglove is

the dried leaves of Digitalis lanata Ehrhart,
a plant indigenous to southern and central
Europe. It is the source of digoxin and
desacetyllanatoside C; however, nearly 70
different glycosides have been detected in
the leaves of D. lanata. The composition of
19 of the most important of these is listed
in Table 7-3. All are derivatives of 5 dif-
ferent aglycones, 3 of which (digitoxigenin,
gitoxigenin, and gitaloxigenin) also occur
in D. purpurea. The other 2 types of gly-
cosides derived from digoxigenin and di-
ginatigenin occur in D. lanata but not in D.
purpurea. As noted in the table, the 5 types
of primary glycosides are designated Ian-
atosides A through E, according to the
identity of the aglycone. The lanatosides
are sometimes referred to as digilanids, es-
pecially in the older literature.

None of the primary glycosides of D. lan-
ata is identical to those found in D. pur-
purea. Even those that have the same agly-
cone differ by the presence of an acetyl
group attached to the third digitoxose res-
idue. Removal of the acetyl group and
sugar residues by selective hydrolysis re-
sults in secondary glycosides, some of
which, e.g., digitoxin, occur in both spe-
cies. Note: Glycosides derived from agly-
cones of the C and D series may be ob-
tained onlv from D. lanata.

Digoxin

Digoxin is the most widely used of the
cardiotonic glycosides, and it is obtained
from the leaves of D. lanata. On hydrolysis
digoxin yields 1 molecule of digoxigenin
and 3 of digitoxose. It is a highly potent
drug and should be t handled with excep-
tional care. Digoxin occurs as a white, crys-
talline powder-,

Digoxin tablets are 60 to 80% absorbed,
and variable bioequivalence among differ-
ent brands of digoxin tablets has been dem-
onstrated. Because of the low therapeutic
index of the drug, it is recommeneded that,
in the absence of good comparative bio-
availability data, a patient should not be
changed from one brand of tablet to an-
other after a reasonable therapeutic effect
has been achieved with one preparation.
Otherwise, either a toxic or nontherapeutic
effect may result owing to a change in the
bioavailability of the drug.

USE AND DOSE. A solution-filled capsule
is available that the manufacturer claims
provides a 1007c bioavailability.

Upon oral administration, the onset of
action is 30 minutes to 2 hours, with a peak
at 2 to 6 hours. Digoxin is also administered
parenterally for a more rapid effect. The
major route of elimination is the kidneys,
and with a plasma half-life of 30 to 40
hours, complete dissipation of effects fol-
lowing discontinuation of therapy takes
from 6 to 8 days. It is estimated that a drug-
serum level of 0.5 to 2 ng/ml is required for
full therapeutic effect, and levels exceeding
2.5 ng/ml may produce symptoms of tox-
icity.

Digoxin has the same uses and precau-
tions as digitalis and is indicated when the
risk of digitalis intoxication is great, since
it is relatively short-acting and rapidly
eliminated when compared with digitoxin.
However, digitoxin may be indicated in pa-
tients with impaired renal function. '

The usual dosage schedule is given in
Table 7-2.

PRESCRIPTION PRODUCTS. Lanoxin®, Lan-
oxicaps®.

STEROIDS

171

Table 7-3. Composition of the Principal Glycosides of Digitalis lanata

Glycoside

Suggs

Derivatives of Digitoxigenin

Lanatoside A
Acetyldigitoxin (a and (3 forms)

Digi toxin

Glu co-eva tromonoside
Gluco-digitoxigcnin-glucomethyloside
Gluco-digifueoside
Neo-gluco-digifucoside

3 digitoxose, 1 acetyl group, 1 glucose
3 digitoxose, 1 acetyl group
3 digitoxose
1 digitoxose, 1 glucose
1 glucomethylose, 1 glucose
1 fucose, 2 glucose
1 fucose, 1 glucose

Derivatives of Gitoxigenin

Lanatoside B 3 digitoxose, 1 acetyl group, 1 glucose

Gluco-gitoroside 1 digitoxose, 1 glucose

Digitalinum verum 1 digitalose, 1 glucose

Lanatoside E

Gluco-lanadoxin

Gluco-verodoxin

Derivatives of Gitaloxigenin

3 digitoxose,
1 digitoxose,
1 digitalose.

Derivatives of Digoxigenin

Lanatoside C 3 digitoxose,

Desacetyllanatoside C 3 digitoxose,

Acetyldigoxin (a, |3, and y forms) 3 digitoxose,

Digoxin 3 digitoxose

Gluco-digoxigenin-bis-digitoxoside 2 digitoxose.

Lanatoside D

Derivatives of Diginatigenin

3 digitoxose,

1 acetyl group, 1 glucose
1 glucose
1 glucose

1 acetyl group, 1 glucose
1 glucose
1 acetyl group

1 glucose

1 acetyl group, 1 glucose

Deslanoside

Deslanoside is desacetyllanatoside C,
which on hydrolysis yields 1 molecule of
digo^genin, 3 of digitoxose, and 1 of glu-
cose. Deslanoside occurs as a white, crys-
talline powder. It is hygroscopic, absorbing
about 7% of moisture when exposed to air,
and is highly potent.

Deslanoside is frequently used to attain
rapid initial loading by parenteral admin-
istration. Onset of action is 10 to 30 min-
utes; maxima] effects occur in 2 to 3 hours,
with dissipation in 3 to 6 days. The usual
dosage schedule, intramuscularly or intra-
venously for digitalization, is given in
Table 7-2. The same precautions of use that
apply to digitalis also applv to deslanoside.

PRESCRIPTION PRODUCT. Cedilanid D®.

Other Cardioactive Drugs

A number of plants contain cardioactive
glycosides, and some of them have been

employed for many years as cardiac stim-
ulants and diuretics. Several are more po-
tent than digitalis, but they are less reliable
because their dosage cannot be controlled
properly. Although most of these drugs
were recognized officially for years and
were considered efficacious, they have
been superseded by digitalis and its deriv-
atives. A few are currently under reinves-
tigation.

Convallaria or lily-of-the-valley root is

the dried rhizome and roots of Convallaria
majalis Linne (Fam. Liliaceae). More than
20 cardioactive glycosides have been iso-
lated from this drug. Principal among these
is convallatoxin, a monoglycoside com-
posed of the genin of K-strophanthin (stro-
phanthidin) and the sugar of G-strophan-
thin (rhamnose). Other minor glycosides
include convallatoxol and convalloside.

Apocynum, black Indian hemp, dog
bane, or Canadian hemp consists of the

172

STEROIDS

dried rhizome and roots of Apocynum can-
nabinum Linne or A. androsaemifolium Linne
(Fam. Apocynaceae). The chief constituent
is cymarin, although apocannoside and
cyanocannoside have also been isolated
from A. cannabinum.

Adonis or pheasant's eye is the dried
overground portion of Adonis vernulis
Linne (Fam. Ranunculaceae). Cardioactive
glycosides identified in the drug include
adonitoxin, cymarin, and K-strophanthin.

Cactus grandiflorus or night-blooming
cereus consists of the fresh, succulent stem
of wild-growing Selenicereus grandiflorus
(Linne) Britton et Rose (Fam. Cactaceae).

Black hellebore or Christmas rose is the
dried rhizome and roots of Helleborus niger
Linne (Fam. Ranunculaceae). The chief
constituent is hellebrin. Black hellebore
possesses cardiac stimulant properties in
contrast to green hellebore (see veratrum
viride), which is a cardiac depressant.

Another plant that contains a cardiac gly-
coside is Nerium oleander Linne (Fam. Apo-
cvnaceae). The leaves have been used to
treat cardiac insufficiency. The chief con-
stituent is oleandrin, a 3-glycosido-16-ace-
tyl derivative of gitoxigenin.

Strophanthus is the dried, ripe seed of
Strophanthus kornbe Oliver, or of S. hispidus
DeCandolle (Fam. Apocynaceae), that is
deprived of the awns. Strophanthus seeds
have long been used by native Africans in
the preparation of arrow poisons. These
poisons were first observed in western Af-
rica by Hen delot and in East Africa by Liv-
ingstone. Early specimens sent to Europe
established the powerful cardiac properties
of the seeds.

K-strophanthoside, also known as
strophoside, is the principal primary gly-
coside in both S. kombe and S. hispidus. It
is composed of the genin, strophanthidin,
coupled to a trisaccharide consisting of cy-
marose, p-glucose, and a-glucose. a-Glu-
cosidase removes the terminal a-glucose to
yield K-strophanfhin-B, and the enzyme,
strophanthobiase, contained in the seed
converts this t b cymarin plus glucose. A

mixture of these glycosides, existing in the
seed in concentrations of up to 5%, was
formerly designated strophanthin or
K-strophanthin. Recent studies have re-
vealed additional glycosides as minor con-
stituents.

Ouabain is a glycoside of ouabagenin
and rhamnose. It may be obtained from the
seeds of Strophanthus gratus (Wall et Hook.)
Baillon or from the wood of Acokanthera
schimperi (A. DC.) Schwf. (Fam. Apocy-
naceae). It is extremely poisonous. Oua-
bain is also known as G-strophanthin.

Squill or squill bulb consists of the cut
and dried, fleshy, inner scales of the bulb
of the white variety of Urginea maritime
(Linne) Baker, known in commerce as
white or Mediterranean squill; or of U. in-
dica Kunth, known in commerce as Indian
squill (Fam. Liliaceae). The central portion
of the bulb is excluded during its process-
ing.

Squill contains about a dozen cardioac-
tive glycosides. The principal one, scillaren
A, comprises about two thirds of the total
glycoside fraction. On hydrolysis, it yields
the aglycone scillarenin, a bufadienolide,
plus rhamnose and glucose. Other minor
glycosides include glucoscillaren A (scilla-
renin + rhamnose + glucose + glucose)
and proscillaridin A (scillarenin + rham-
nose).

Squill is an expectorant, but it also pos-
sesses emetic, cardiotonic, and diuretic
properties.

Red squill consists of the bulb or bulb
scales of the red variety of U. maritima,
which is imported for use as a rat poison.
It should not be present in the medicinal
squill and may be detected by the presence
of red, pink, or purple epidermal or pa-
renchymal tissues.

Most of the squill imported into the
United States is of the red variety. Each
year, a considerable tonnage is used as a
rodenticide. Rodents lack the vomiting re-
flex, which makes red squill particularly
lethal to these animals. The inadvertent

STEROIDS

173

ingestion by human beings of plant ma-
terials that contain cardiac glycosides in-
duces the vomiting reflex and reduces the
life-threatening aspects of the toxic mani-
festations.

STEROID HORMONES

The steroid hormones can be divided
into 2 classes, the sex hormones and the
adrenocortical hormones. The former are
produced primarily in the gonads and me-
diate the growth, development, mainte-
nance, and function of the reproductive
tract and the accessory sex organs. These
hormones fall into 3 chemically and phys-
iologically distinct categories: the estrogens
and progestins, which regulate various
functions of the female reproductive tract,
and the androgens, which stimulate the
development of the male reproductive or-
gans. The adrenocortical hormones are
produced by the outer cortical portion of
the adrenal glands, and they are divided
into 2 classes, depending on their biologic
activity. The hormones that principally af-
fect the excretion of fluid and electrolytes,
with a subsequent sodium retention, are
called mineralocorticoids; those that affect
intermediary metabolism are termed glu-
cocorticoids.

The production of steroid hormones in
the body is initiated by the releasing factors
of the hypothalamus, which travel to the
anterior lobe of the pituitary gland where
they induce the release of tropic hormones
into the blood. When stimulated by the ap-
propriate tropic hormone, steroids are syn-
thesized at the target site, either the ad-
renal cortex or the gonads. Steroid level in
the blood is held in balance by a mecha-
nism of feedback regulation that is me-
diated through the hypothalamus. When
excess active steroid is in the blood that
reaches the hypothalamus, the production
of the hypothalamic releasing factors is
stopped (Fig. 7-11).

This phenomenon of feedback regula-
tion can cause problems in drug therapy

f — + ( Hypothalamus)

Feedback

Regulation Releasing factor

1

i (Anterior Pituitary" )

!■ i

Tropic hormone

I ‘ i

; (Adrenal Cortex or G onads N ?

I _ I

Steroid hormone

_ i

(Targe t Tissue )

Fig. 7-11. Regulation of steroid hormone produc-
tion.

with steroid hormones. For example, pro-
longed therapy with corticosteroids may
cause irreversible atrophy of the adrenal
cortex. A high corticosteroid level in the
body suppresses the hypothalamus from
secreting the corticotropin -releasing factor
which, in turn, suppresses release of cor-
ticotropin. The lack of stimulatory impact
of this anterior pituitary' hormone result-
in atrophy of the adrenal cortex.

Biosynthesis of Steroid Hormones. Biosyn
thesis of the numerous steroid hormone:
of the adrenal cortex, gonads, and placenta
is an extremely complex specialty field.
Only the briefest essentials can be pre-
sented here. When one realizes that more
than 70 different steroids have been iso-
lated from the adrenal gland alone, one can
easily understand why the biosynthetic re-
lationships are complex.

Like other steroids of biologic origin,
these hormones are derived from the well-
known acetate-mevalonic acid pathway
which, in this case, leads first to cholesterol
(see Fig. 7-3 for details). Partial side-chain
degradation of cholesterol leads to preg-
nenolone and then to progesterone, both
of which serve as precursors of the other
steroid hormones.

The conversion of cholesterol to preg-

174

STERQjPj

nenolone is catalyzed by a mixed-function
oxidase enzyme complex that involves a
desmolase and requires 0 2 and NADPH.
This conversion appears to be the rate-lim-
iting step in steroid hormone biosynthesis
and is under the influence of the tropic
hormones of the anterior pituitary. In the
case of ACTH stimulation of steroidogen-
esis, ACTH activates adrenal cortical ad-
enyl cyclase, which causes a rise in cyclic
AMP and a subsequent activation of gly-
cogen phosphorylase. This enzyme breaks
down glycogen to produce glucose-6-phos-
phate, which then is oxidized via the hex-
ose monophosphate shunt pathway, yield-
ing NADPH. An increase in the availability
of this coenzyme increases the activity of
the desmolase and the hydroxylase reac-
tions.

Enzymes in the adrenals and the gonads
remove the side chain and hydroxylate the
steroid nucleus in the 17 a-position to form
the androgens. After loss of the angular 19-
methyl group, androgens are aromatized
to estrogens. The adrenals also hydroxyl-
ate progesterone in positions 21, 11, and/
or 17 to produce the classic adrenocortical
hormones. Production of aldosterone in-
volves 18-hydroxylation and dehydrogen-
ation reactions.

Some of the principal conversions are il-
lustrated in the simplified scheme shown
in Figure 7-12.

The steroid hormones are bound to pro-
teins, primarily albumins, for transport in
the blood. These steroid-protein complexes
per se are physiologically inert and protect
the steroid from metabolic inactivation.
The strength of binding varies and can be
generalized by classification as follows: the
corticosteroids tend to be weakly bound,
the estrogens are more strongly bound,
and progesterone and testosterone are in-
termediate between the 2 extremes.

Reductive processes are normally in-
volved in the metabolism of steroid hor-
mones. The di-, tetra-, and hexahydric me-
tabolites may be formed and usually entail
progressive reduction of the 4-ene, 3-keto,

and 20-keto functions. The reduced forms
are usually excreted as the more soluble
uronides or sulfate esters involving the
3-oxygen function. In the case of the me-
tabolism of estradiol and testosterone, the
initial metabolic reaction is oxidative, in-
volving the 17-hydroxyl function, but sub-
sequent metabolic steps are reductive, with
eventual conjugation.

Mechanism of Action. The steroid hor-
mones have diverse actions, and several
specific receptor proteins, varying with the
particular target tissue, have been isolated
for each action. Structural changes of the
hormone may affect the affinity or activity
on one receptor and have little or no effect
on other receptors. For example, changes
in the chemical structure of testosterone
allow for the separation of the androgenic
activity from the anabolic activity of this
hormone. The same applies when sepa-
rating the glucocorticoid/mineralocorticoid
activity of corticosteroids. Also, steroid
hormones do not act through an increase
in cyclic AMP but rather through a stim-
ulation of protein synthesis. A possible ex-
planation of this mechanism is that the ste-
roid binds with the specific receptor
protein in the cytoplasm of the target cell.
This complex enters the nucleus, where it
is bound to the chromosome through a spe-
cific acceptor protein associated with chro-
matin. The interaction of steroid, of cyto-
plasm receptor protein, and of the
chromosomal receptor protein may lead to
a derepression of a segment of chromo-
some, which would result in the increased
production of a particular enzyme protein.
For example, mineralocorticoids produce
an increase in the synthesis of enzymes
that are necessary for active transport of
Na + , which leads directly to increased Na +
reabsorpfion in the renal tubules.

Commercial Production of Steroids. Ihe ste-
roid hormones and their semisynthetic an-
alogs represent a multimillion -dollar an-
nual business for the American drug
industry. When one considers the social,
political, and economic implications asso-

Steroids

Steroids constitute a natural product
class of compounds that is widely distrib-
uted throughout nature. The diversity of
biologic activities of steroids includes the
development and control of the reproduc-
tive tract in humans (estradiol, progester-
one, testosterone), the molting of insects
(ecdysone), and the induction of sexual re-
production in aquatic fungi (antheridiol).
In addition, steroids contribute to a wide
range of therapeutic applications, such as
cardiotonics (digitoxin), vitamin D precur-
sors (ergosterol), oral contraceptive agents
(semisynthetic estrogens and progestins),
anti-inflammatory agents (corticosteroids),
and anabolic agents (androgens).

NOMENCLATURE

A steroid is any compound that contains
a cyclopentanoperhydrophenanthrene nu-
cleus. The chemical nomenclature of ste-
roids is based on this fundamental carbo-
cycle with adjacent side-chain carbon
atoms. Each parent tetracyclic hydrocarbon
bears a specific stem name, and some of
the principal hydrocarbons are shown in
Figure 7-1. Steroids are numbered and
rings are lettered as indicated in the struc-
tural formula for cholesterol. If one or more
of the carbon atoms shown in the structure
of cholesterol is not present, the number-
ing of the remainder is undisturbed.

When the rings of a steroid are denoted
as projections onto the plane of the paper,
an atom or group attached to a ring is
termed a (alpha) if it lies below the plane
of the paper or (3 (beta) if it lies above the
plane of the paper. In formulas, bonds to
atoms or groups attached in an a config-
uration are shown as broken lines, and
bonds to atoms or groups attached in a (3
configuration are shown as solid lines.

The use of a steroid stem name implies
that atoms or groups attached at the ring-
junction positions 8, 9, 10, 13, and 14 are
oriented as shown in Figure 7-2 (8(3, 9cx,
10p, 13p, 14a), and a carbon chain (R) at-
tached to position 17 is assumed to be
P-oriented. The configuration of hydrogen
or a substituent at the ring-junction posi-
tion 5 is always designated by adding a or
P after the numeral 5. This numeral and
letter are placed immediately before the
stem name. The implication of these con-
ventions of nomenclature is that, in most
steroids, rings B and C and rings C and D
are fused trans, whereas rings A and B may
be fused either cis or trans. For example,
the bile acid, cholic acid, has a cis - fused ‘A f

156

RESINS AND RESIN COMBINATIONS

155

coniferyl benzoate (60 to 70%), plus smaller
amounts of free benzoic acid (10%), the tri-
terpene, siaresinol, (6%), and a trace of va-
nillin.

Sumatra benzoin contains free balsamic
acids, chiefly cinnamic (10%) and benzoic
(6%), as well as esters derived from them.
Triterpene acids, especially 19-hydroxy-
oleanolic and 6-hydroxyoleanolic, and
traces of vanillin, phenylpropyl cinnamate,
cinnamyl cinnamate, and phenylethyiene
are also present.

Sumatra benzoin yields not less than
75% of alcohol-soluble extractive; Siam
benzoin yields not less than 90% of alcohol-
soluble extractive.

USES. Benzoin possesses antiseptic, stim-
ulant, expectorant, and diuretic properties.

Compound benzoin tincture is em-
ployed as a topical protectant and is ap-
plied as required. It contains benzoin, aloe,
storax, and Tolu balsam and is valuable as
an expectorant when vaporized.

PROPRIETARY PRODUCT. VapoSteam®.

Benzoic acid is now a synthetic product
but was first obtained by sublimation from
Sumatra benzoin.

It occurs as white crystals, usually in the
form of scales or needles. It has a slight
odor of benzoin and is volatile at moderate
temperatures, freely so in steam.

Benzoic acid and its sodium salt are ex-
tensively used as preservatives of foods,
drinks, fats, pharmaceutic preparations,
and other substances. Medicinally, benzoic
acid is used primarily as an antifungal
agent. It is an ingredient in benzoic and

salicylic acids ointment (Whitfield's oint-
ment), which is effective in the treatment
of athlete's foot and, to a lesser extent,
ringworm.

READING REFERENCES

Agurell, 5., Dewey, W.L., and Willette, R.E., eds.:
The Cannabinoids: Chemical , Pharmacologic, and
Therapeutic Aspects, Orlando, Florida, Academic
Press, Inc., 1984.

Balbaa, S.I., Karawya, M.S., and Girgis, A.N.: The
Capsaicin Content of Capsicum Fruits at Different
Stages of Maturity, Lloydia, 32 (3):272, 1968.
Bernfeld, P., ed.: Biogenesis of Natural Compounds, 2nd
ed.. New York, Pergamon Press, Inc., 1967.
Efron, D., ed.: Ethnopharmacologic Search for Psychoac-
tive Drugs, Public Health Service Publication No.
1645, Washington, D.C., U.S. Government Print-
ing Office, 1967.

Ernmenegger, H., Stahelin, H., Rutschmann, J.,
Renz, J., and von Wartburg, A.: Zur Chemie und
Pharmakologie der Podophyllum-G\ucoside und
ihrer Derivate, Arzneim. Forsch., 11 (4,5):32 7,
459, 1961.

Fehr, K.O., and Kalnnt, H., eds.: Cannabis and Health
Hazards, Toronto, Addiction Research Founda-
tion, 1983.

Guenther, E.: Ginger in Jamaica, Coffee and Tea Ind.,
S2(l):169, 1959.

Howes, F.N.: Vegetable Gums and Resins , Waltham,
Massachusetts, Chronica Botanica Co., 1949.
Mantell, C.L., Kopf, C.W., Curtis, J.L., and Rogers,
E.M .. The Technology of Natural Resins , New York,
John Wiley & Sons, Inc., 1942.

Pravatoroff, N.: Ginger — The Properties and Chem-
istry of Some Natural Spicy Compounds, Mfg.
Chemist, 38(3):40, 1967.

Schroeder, H.A.: The /.’-Hydroxycinnamyl Com-
pounds of Siam Benzoin Gum, Phytochemistry
7(1):57, 1968.

Walker, G.T.: Balsam of Peru, Perfumery Essent. Oil
Record, 5.9(10):705, 1968.

Waller, C W., et al.: Marihuana: Art Annotated Bibliog-
raphy, Vols. I and II plus Supplements, New York,
and University, Mississippi, Macmillan and Re-
search Institute of Pharmaceutical Sciences, Uni-
versity of Mississippi, 1976-1982.

STEROIDS

IZi

20,22 Dihydroxy Cbotesterttf

T* CH,OH

Progesterone

Corticosterone

17.> hydroxylase

17aHydroxyprogesterone

Testosterone

OH

Estradiol

Pregnenolone

Fig. 7-12. Biosynthesis and bioconversion of steroid hormones.

ciated with the use of oral contraceptive
drugs, the importance of steroids to man-
kind cannot be questioned. At the present
time, the principal source of the steroid
chemical nucleus used in the drug industry
is the plant kingdom; however, in the not
too distant past, the source of steroid hor-
mones was from the gonads and adrenal
glands of animals that were used as food
by humans. The amount of hormone pres-
ent in these glands was extremely small,
and large quantities of glands were re-
quired to isolate milligram quantities of
hormone; consequently, it was not practi-
cal to use the pure hormone in therapy. For
example, in 1934, Schering Laboratories,
Berlin, needed 625 kg of ovaries from
50,000 sows in order to obtain 20 mg of
pure crystalline progesterone.

Today, the steroid industry represents
the culmination of efforts by many scien-

tists; however, a few can be singled out for
their pioneering work in steroid chemistry
One of these men is Russell E. Marker
Marker is responsible for the discovery oi
a commercially feasible conversion of ster-
oidal sapogenins to progesterone. His
early work involved the search for plant
species that were rich in steroidal sapo-
genins. When he found that Mexican
yams, various species of Dioscorea, were
rich in these compounds, he moved to
Mexico City in 1943, where he isolated
diosgenin from D. macrostachya (D. mexi-
cana), known in Mexico as cabeza de negro.
From diosgenin, employing the chemical
degradation illustrated in Figure 7-13, he
managed to prepare more than 3 kg of pro-
gesterone (at the time valued at $8 a gram).
This hormone and the process used to pre-
pare it were the foundation stones for the
Syntex Company.

176

STEROIDS

H A ^ „

"1 i V- CH,

CH 3 | N, /

V'' AC,0

CHj CH,C— 0 \

V - iv / — CH,

CHJ K / 3

Pyritjine HCI

Diosgenin

CH

CH 3 CO‘ "

r

Pseudodiosgenin Acetate

CH,

CH 3 ,

CH 3^- 0

0

!!

CH,CO

CH

J

0 ! i

3k

CH

Diosone Acetate

CH 3

CH,

-k K

$*C>

KOH CrQ,

CH

Pregnadienolone Acetate

CH,

\

CH, > 0

0

it —

CH 3 C0

Pregnenolone Acetate
Fig. 7-13. The Marker degradation.

Progesterone

During the 1930s, several scientists, in-
cluding E. C. Kendall, a chemist at the
Mayo Clinic, and T. Reichstein, a chemist
at the Federal Institute of Technology, Zu-
rich, Switzerland, almost simultaneously
and independently isolated steroids from
the adrenal cortex of cattle. Stimulated by
the potential therapeutic importance of
these compounds, the Merck Company in
1944 successfully produced 15 mg of cor-
tisone from 1 kg of desoxycholic acid uti-
lizing 36 separate chemical steps. How-
ever, in 1949, when P.S. Hench of the
Mayo Clinic announced cortisone's dra-
matic effectiveness in treating rheumatoid
arthritis, the increased demand for corti-
sone required a more readily available and
inexpensive source. The problem was
solved in 1952 when scientists at the Up-

john Company found a microorganism,
Rhizopus arrhizus, that could convert pro-
gesterone, a readily available starting ma-
terial because of the Marker degradation,
to lla-hydroxyprogesterone in an 80 to
90% yield. The extremely difficult problem
of introducing an oxygen function in the
11-position of the steroid nucleus by using
chemical methods was therefore solved
(Fig. 7-14).

A vast amount of research resulted in
extension and improvement of this basic
procedure with other precursors and nu-
merous microorganisms. Relatively inex-
pensive starting materials, such as stig-
masterol from soybeans, hecogenin from
the sisal industry, or diosgenin from Dios -
corea species, are now employed.

Stigmastejol may be converted chemi-

STEROIDS

177

Fig. 7-14.

Progesterone

Rhtzopus arrhizus

also species of
Aspergillus, Dactylium
and Cephalcthecium

CH,
l 3
c=o

1 la>Hydroxyprogesterone

Introduction of oxygen function into the 11-position of the steroid nucleus.

cally to progesterone, which is, in turn,
incubated in large fermentors with suitable
microorganisms under specified condi-
tions to yield lla-hydroxyprogesterone,
which may then be converted chemically
to cortisone. Similarly, cortexolone (Reich-
stein's substance S) is prepared chemically
from diosgenin and is then converted by
Strcptomyces fradiae or Cunninghamella blak-
esleeana to cortisol (hydrocortisone).

Cortisone or cortisol is dehydrogenated
in the A ‘-position by Corynebacterium sim-
plex or by Fusarium species to yield pred-
nisone or prednisolone, respectively.

Certain microorganisms also can hy-
droxylate synthetically prepared fluoro-
steroids in the 16a-position to produce
triamcinolone (Fig. 7-15).

Adrenal Cortex

The adrenal cortex is essential to life. Re-
moval of about 85% of cortical tissue is le-
thal in a few days. In animals so treated,
life may be maintained by the administra-
tion of extracts of hormones of the adrenal
cortex.

Cortical deficiency in animals is marked
by a loss of appetite and weight, vomiting
and diarrhea, weakness, and a fall in tem-
perature, metabolism, and blood pressure
There is a loss of blood fluid, with resulting
concentration of blood, and a fall in serum
sodium, with a rise in serum glucose and
potassium. Kidney damage is frequently
present. These developments can be pre-
vented or restored to normal by the admin-
istration of cortical extracts and frequently

by the simple use of a high sodium, low
potassium intake.

The human counterpart of this defi-
ciency picture is seen in the clinical devel
opment of Addison's disease (chronic ad
renocortical insufficiency), usually owin
to tuberculosis or tumor of the adrenal cor
tex. Associated with this disease are de-
generation of the gonads, a marked in
crease in capillary permeability, and ar
increased sensitivity to insulin. Sodium
loss with potassium retention may be the
outstanding condition of the disease. If un
treated, Addison's disease terminates fa
tally in 1 to 3 years, usually owing to hy
poglycemia, dehydration, nutritiona
disturbances, or secondary infection.

Excessive adrenal cortical activity, as ir
tumors or because of the presence of ac
cessory cortical tissue, results in profounc
growth abnormalities, especially seen in
the external genitalia and in the secondary
sex characteristics. In young children,
there is precocious sexual development
and desire and obesity or unusual mus-
cular development. In adult females, viril-
ism usually develops, associated with a
masculine appearance, often with homo-
sexuality. The bearded lady of the circus
frequently falls into this category. Treat-
ment of cortical hyperactivity is principally
surgical.

Some 70 or more steroids have been iso-
lated from cortical extracts. These exhibit
in some degree the action of adrenal cortex.
Some, in addition, manifest estrogenic, an-
drogenic, and progesteronelike activity.

Sfrepfomyces Iradiae or
run mnebameHa biafceslee ana^

Cortexolone

Cortisol

CH.OH

|

c=o

ch 2 oh

C-0

OK,

T

CHj|

i

a OH

Cor/nebacteri'KV simplex
or

Fusanum sp.

Cortisone (R — 0)
Cortisol (R = OH)

Prednisone (R =■ O)
Prednisolone (R = OH)

Srrep^omyces Sp.

ch 2 oh

C—O

, FlrOH

ch 3 |

HO

'tt

9o-Fluorocortisol

Mycobacterium sp

i

CH,OH

I

c=o

CH 3 i | j.

Streptc myces sp_

16n -Hydroxy-9a -fluorocortisol

| Corynebacterium sp.
*

CH 2 OH

0-0

fU

4 * > 0H

9 a-Fluoroprednisolone

Triamcinolone

Fig 7-15. Microbiologic transformation in production of glucocorticoids.
^eH—^ec.o^aUon.MpJ-

Iny

sone, hydrocortisone, desoxycorhcoSte - - are consi dered primarily glu-

one, and aldosterone. Corhsone and agen s variable mineralocor-

drocortisone constitute the majoncy of the cocor P ^ ^

hormones that regulate protein and ca pr ions of the adrenal cortex are

bohydrate metabolism They hav - .be* ^ QSt effectively in replacement ther-
ferred to as the glucocorhcouls. Aidc S such con ,; itions as Addison’ s ±s-

one and desoxycortKOStw h ; vc oe P caused adrenal cortex de-

ferred to as mmemlocorhco.o? *Mi> -

STEROIDS

179

ficiency. An injection containing a mixture
of hormonal substances from the adrenal
cortex has been used in replacement ther-
apy. Presumably, use of such a crude mix-
ture offers the advantage of administering
all of the active glandular hormones rather
than only individual hormones that have
been recognized and are available in pure
form. However, controlling responses with
undefined preparations is difficult, and the
subtle responses potentially elicited by the
mixed extracts are not easily recognized;
thus, the trend in replacement therapy fa-
vors the use of pure hormonal substances.

The glucocorticoids are also used for
their anti-inflammatory activity; therapy
based on this pharmacologic response is an
effective palliative approach in rheumatoid
arthritis and a number of other conditions
involving the inflammatory response.
However, caution must be used in balanc-
ing the advantages and disadvantages of
prolonged administration of corticosteroid
therapy, such as may be involved in ar-
thritic conditions. Exogenous sources of
corticosteroids may cause a disruption in
the physiologic balance among the biosyn-
thetically related steroid hormones; toxic
manifestations in such situations often in-
volve changes that are normally consid-
ered to be dominated by gonadal hor-
mones. As was discussed earlier, another
potential problem of serious consequence
is irreversible atrophy of the adrenal cor-
tex.

Glucocorticoid therapy provides pallia-
tive treatment of symptoms in many al-
lergic disorders, such as bronchial asthma,
and is lifesaving for patients in anaphylac-
tic shock. These compounds are used as
immunosuppressive agents in organ trans-
plants and autoimmune disorders and as
antitumor agents in the treatment of ma-
lignancies, especially in certain leukemias
and lymphomas.

Drug Interactions. Barbiturates and pheft-
ytoin can induce the hepatic drug-metab-
olizing enzymes, such as hydrocortisone
hydroxylase, which results in an increased

degradation of corticosteroids. Therefore,
concomitant therapy with one of these
drugs may require an increase in the dose
of the corticosteroid.

Because of an increase in hepatic glu-
coneogenesis during glucocorticoid ther-
apy, the dose of hypoglycemic agents may
have to be adjusted upward in diabetic pa-
tients receiving corticosteroids.

Desoxycorticosterone or desoxycortone
is 21-hydroxypregn-4-ene-3,20-dione, a
steroid hormone that was identified by
Reichstein and his associates in 1938. Later,
it was synthesized from stigmasterol. Pres-
ent drug supplies are obtained by synthetic
means.

This hormone is classified as a mineral-
ocorticoid. Desoxycorticosterone functions
primarily to restore a balance of sodium
and potassium in body fluids and to restore
kidney function in cortical deficiency.
Death from hypoglycemia may occur w T hen
Addison's disease is treated with desoxy-
corticosterone alone; such cases also re-
quire the use of a glucocorticoid.

2 OCOCH 3

Desoxycorticosterone Acetate

The hydroxyl function at C-21 of desox-
ycorticosterone is esterified, normally with
acetic acid, in pharmaceutic formulations.
It is effective when administered buccally,
but better and more uniform results follow
intramuscular injection. Pellets can be suc-
cessfully implanted in the subcutaneous
tissues for even more prolonged action.
The usual dose of desoxycorticosterone
acetate, intramuscularly or subcutane-
ously, is 1 to 5 mg daily.

PRESCRIPTION PRODUCTS. Doca Acetate®,
Percorten Acetate®, Percorten Pivalate®
(the trimethylacetate'ester).

180

STEROIDS

Cortisone or 17,21-dihydroxypregn-4-
ene-3,ll,20-trione is one of the glucocor-
ticoid substances of the adrenal cortex. The
acetate ester of this hormone is used intra-
muscularly, orally, and topically to treat a
wide variety of situations, such as rheu-
matoid arthritis, other collagen diseases,
Addison's disease, and certain allergic and
asthmatic conditions. An appreciable
sodium-retaining property can be a major
problem with the systemic use of cortisone.
The usual dose, orally, is 25 to 300 mg a
day; intramuscularly, 20 to 300 mg a day.

PRESCRIPTION PRODUCT. Cortone® Ace-
tate.

CH.OCOCH,
i 2
c=o

Cortisone Acetate

Cortisol or hydrocortisone (Kendall's
compound F) is lip,17,21-trihydroxy-
pregn-4-ene-3,20-dione. It is considered
the principal glucocorticoid substance of
the adrenal cortex. This hormone and its
acetate ester are used intramuscularly, or-
ally, and topically for the same purposes
as cortisone acetate. Intra -articular admin-
istration of cortisol always involves the ace-
tate ester. Hydrocortisone sodium phos-
phate and hydrocortisone sodium
succinate are water-soluble and are used in
parenteral formulations when intravenous
administration is indicated.

There are indications that cortisol is
slightly more potent in some patients than
cortisone and gives slightly better overall
effects. However, it may exhibit the same
disadvantages of sodium retention that
were noted with cortisone.

The usual oral dose of hydrocortisone is
20 to 240 mg daily as a single dose or in
divided doses. Topically, it is applied as a

0.5 to 2.5% cream or ointment. Hydrocor-
tisone acetate is usually administered intra-

articularly, intralesionally, or by soft-tissue
injection, 5 to 75 mg at each site, repeated
at 2- to 3-week intervals. Both hydrocorti-
sone sodium phosphate and hydrocorti-
sone sodium succinate are employed intra-
venously or intramuscularly in usual doses
equivalent to 100 to 500 mg of hydrocor-
tisone, repeated at 2- to 6-hour intervals,
depending upon patient response.

PRESCRIPTION PRODUCTS. Cortef®, Cor-
tef® Acetate, Solu-Cortef®, Hydrocor-
tone®, Hydrocortone® Phosphate.

The potential therapeutic utility of the
glucocorticoids has promoted intensive ef-
forts to discover modifications of the nat-
urally occurring hormones that will be
more potent and more specific in their ac-
tivity. The best success has been achieved
with desired increases in potency. Pred-
nisone (Deltasone®, Meticorten®) and
prednisolone (Delta-Cortef®, Sterane®)
represent early achievements in these ef-
forts. Elimination of any mineralocorticoid
activity has been a major objective; a de-
gree of success has been attained with such
compounds as betamethasone (Celes-
trone®), dexamethasone (Decadron®, Dex-
one®, Hexadrol®), methylprednisolone
(Medrol®), paramethasone (Haldrone®),
and triamcinolone (Aristocort®, Kena-
cort®), but the ideal of total separation of
mineralocorticoid activity from glucocorti-
coid substances has not yet been achieved.
It is interesting to note that successful mod-
ifications in the basic steroid molecule fall
into 4 categories:

1 . A^dehydrogenation

2 . 1 6a-hy droxy la tion

3. 6a- or 9a-fluorination

4. 6a-, 16a-, or 16p-methylation.

Gonads

The ovaries and testes are exocrine (ova,
sperm) as well as endocrine (hormonal) in
function. They develop under the influ-
ence of anterior pituitary hormones, par-
ticularly:

1. The follicle-stimulating hormone
(FSH)Jeads to the development of the

STEROIDS

181

ovarian follicles, to their formation of
ova and of estrogen, and to the de-
velopment of the testes and the mat-
uration of the spermatozoa.

2. The luteinizing hormone (LH) is nec-
essary to the development of the cor-
pora lutea in the ovarian follicles after
ovulation, to the formation of pro-
gesterone by the corpora lutea, and
to the production of androgen in the
matured testis.

Androgens (male hormones) and estro-
gens (female follicular hormones) act to:

1. Develop and maintain the secondary
characters of sex.

2. Depress anterior pituitary function,
leading in turn to the depression of
the testis or the ovary.

Progesterone (corpus luteum hormone)
similarly depresses anterior pituitary func-
tion and presents a mixed antagonism-syn-
ergism with estrogenic activity, as will be
indicated later.

Gonadal hyperactivity or excessive ther-
apy may thus result in a picture of preco-
cious or excessive sexual development,
with the generalized effects of anterior pi-
tuitary depression. Gonadal hypoactivity,
as occurs in the natural menopause or fol-
lowing surgical removal of the gonads, re-
sults in a mixed picture of sexual regression
and enhanced anterior pituitary activity,
with psychic disturbance and the involve-
ment of other endocrine glands, particu-
larly the thyroid.

Testes

Following castration in the male, the sex
organs atrophy, and sexual desire and ac-
tivity are diminished. These functions are
restored by the administration of testis hor-
mone. Hypogonadism (eunuchoidism) is
inadequate development of the testes
owing to pituitary disorder, infection, or
other disease. Therapy of this condition is
still in the experimental stages.

Hypergonadism is most frequently seen
in young males, owing to testis tumors;

this results ^ precocious development of
sex organ* a Ad male characteristics. Ther-
apy is usuafy surgical.

Testosfcawve is believed to be the true
testis h^nione, although it has been iden-
tified only in the bull's testis. It was syn-
thesized by Ruzicka from cholesterol in
1 936. Androsterone and dehydroandros-
terone are urinary excretion products, rel-
atively inactive in man.

Testis hormone preparations have been
valuable in the replacement therapy of
male castrates and eunuchoid states and in
the treatment of certain female ovariar
dysfunctions. Much of this therapy is stil
in the experimental stages. Testosterone i
not an aphrodisiac, and its use may prt
duce the general effects of anterior pitui
taiy depression. It may produce virilism ir
the female, and skin reactions similar t»
acne vulgaris may frequently develop.

Anabolic effects, especially with regard
to protein synthesis and nitrogen retentior
in the body, have been noted with andre
gens. This action is potentially useful a
supportive therapy in a number of debili
tating conditions. Attempts have bee
made to prepare steroid compounds th
separate anabolic effects from other andr
genic activities, and the ultimate limit,
tions on this therapeutic approach ar
keyed to the success of these efforts. Th<
ideal separation has not been achieved
with such compounds as methylandros-
tenediol, methandrostenolone, and other
anabolic substances that are currently
available.

Testosterone or 170-hydroxyandrost-4-
en-3-one is the active male hormone. The
quantities used for drug purposes are pre-
pared synthetically. The 17-hydroxyl func-
tion of testosterone is readily oxidized and
metabolized to the much less physiologi-
cally active keto compound. Thus, testos-
terone is not administered orally. The hor
mone may be used buccally, implanted
subcutaneously, or injected intramuscu-
larly. However, many formulations for
these purposes utilize derivatives of the

182

STEROIDS

hormone, such as the cypionate, ethan-
thate, and propionate esters of the 17-hy-
droxyl group, which are characterized by
delayed absorption and destruction. The
usual dose of testosterone, intramuscu-
larly, is 25 mg as needed; implantation, 150
to 400 mg every 3 to 6 months.

PRESCRIPTION PRODUCTS. Delatestryl®,
Depo-testosterone®.

The introduction of a methyl substituent
at C-17 is another manipulation that has
been used to circumvent the chemical and
metabolic instability of testosterone. Prep-
arations of methyltestosterone (Android®,
Metandren®, Oreton® Methyl) are used
buccally and orally for androgenic pur-
poses.

Testosterone

Ovary

The human ovaries are paired organs.
One is situated on each lateral pelvic wall
in the posterior layer of the broad ligament,
behind and below the lateral extremity of
each fallopian tube (oviduct). Each is about
the size and shape of an unshelled almond
and weighs about 4 to 8 g.

Ova develop within primitive ovarian
follicles (graafian follicles) under the influ-
ence of the follicle-stimulating hormone of
anterior pituitary. Ovulation with the ex-
trusion of one ovum from a ripened follicle
normally occurs each month during the
childbearing period. The ruptured follicle
undergoes cellular change to become the
corpus luteum under the influence of the
luteinizing hormone of the anterior pitui-
tary. The ovary elaborates 2 types of hor-
mones: the estrogens, elaborated in the de-
veloping graafian follicle and probably also
in the placenta during pregnancy; and the
progestins, normally elaborated by the cor-

pus luteum and, in the later half of preg-
nancy, by the placenta.

Estrogens. Deficiency in estrogenic activity
is most frequently experienced in the nor-
mal menopause or following surgical re-
moval of the ovaries. Local changes in the
tissues of the vagina and vulva may result
from estrogenic deficiency of any cause.
The estrogens are necessary to:

1. Develop and maintain secondary fe-
male sex characteristics.

2. Develop and maintain the uterus and
the vagina.

3. Aid in the presecretory development
of the mammary 7 glands.

4. Act as a growth hormone for uterine
smooth muscle cells during preg-
nancy.

Estrogens act further to excite or sensi-
tize the uterine muscle and to depress the
anterior pituitary function. Preparations of
estrogenic substances are employed in the
management of:

1. Symptoms of the natural or surgical
menopause.

2. Local atrophic and degenerative
changes in the adult vagina and
vulva, resulting from estrogen defi-
ciency.

3. Gonorrheal vaginitis in the young fe-
male child, by inducing an adult type
of vaginal epithelium resistant to the
gonococcus.

4. Suppression of lactation in engorged,
painful mammary glands, presum-
ably by a direct action in the breast.

5. Prostatic cancer in the male, presum-
ably by balancing an excessive per-
sistence of androgen — the principle
of "biochemical castration."

The natural ovarian hormones are ste-
roids. The 3 major estrogenic hormones are
estradiol and its oxidation products, es-
triol, and estrone. These hormones can be
isolated from urine during pregnancy and
can be prepared synthetically. Other estro-
genic substances occur naturally, and
amorphous mixtures of some of these ste-
roids obtained from a pregnant mare's

STEROIDS

183

urine are used in therapy under the des-
ignations of conjugated and esterified es-
trogens.

Estrogens may be administered orally,
parenterally, by implantation, or by inunc-
tion for systemic activity. Orally adminis-
tered natural estrogens are destroyed in
greater part. Estriol is the best of the pure,
naturally occurring estrogens for oral use;
oral efficiency of estriol is about one-fifth
that achieved by parenteral administration.
Conjugated and esterified estrogens are
also used orally, and the introduction of an
ethinyl substituent at C-l 7 of estradiol
gives a potent, orally effective compound;
the usual dose of ethinyl estradiol (Esti-
nyl®, Feminone®) is 50 pg, 1 to 3 times a
day.

As much as 90% of parenterally admin-
istered natural estrogens may be de-
stroyed. This factor, in addition to rapid
absorption, tends to diminish their effi-
ciency and the effective period of therapy.
Pharmaceutic manipulations, which have
proved useful in achieving a prolonged ac-
tion, include the use of esters, such as
cypionate or valerate, and of formulations
involving sterile vegetable oils. These ma-
nipulations slow absorption and destruc-
tion of the hormones; they also lessen the
side effects of nausea and vomiting.

Implantation of the estrogens or their es-
ters provides an even longer duration of
action than do preparations administered
intramuscularly. Suppositories containing
estrogenic substances provide local treat-
ment of changes in the vagina or vulva, or
treatment of gonorrheal vaginitis in female
children, with a minimum of systemic ef-
fect.

The natural estrogens exhibit carcino-
genic properties upon prolonged admin-
istration to animal strains having heredi-
tary susceptibility to mammary cancer. On
this basis, some feel that use of estrogens
should be contraindicated in women who
have a personal or family history of mam-
mary or genital cancer.

Estradiol. Estradiol or estra-

1,3,5(10) — triene-3,17p-diol is used orally,
injected intramuscularly, and implanted
subcutaneously. The usual dose, orally, is
1 to 2 mg daily; implantation, 25 mg, as
necessary.

OH

The usual intramuscular maintenance
doses of the estradiol esters are 1 to 5 mg
every 1.5 to 2 months for the cypionate
(Depo-Estradiol®) and 10 to 20 mg every 4
weeks for the valerate (Delestrogen®).

Estrone. Estrone or estra-l,3,5(10)-trien-3-
ol-17-one is used intramuscularly. The
usual dose is 100 to 500 pg 2 to 3 times a
week for menopausal symptoms.

PRESCRIPTION PRODUCT. Theelin®.

The designation conjugated estrogens
refers to a mixture of the sodium salts of
the sulfate esters of the estrogenic sub-
stances that are of the type excreted by
pregnant mares. This mixture of estrogenic
substances must contain not less than 509 ,
and not more than 65% of sodium estrom
sulfate and not less than 20% and not mon
than 35% of sodium equilin sulfate. Equilin
is estra-l,3,5(10),7-tetraen-3-ol-17-one and
is one of the estrogens that appears in preg-
nant mare's urine in increasing quantities
as the stage of pregnancy advances; equilin
is only slightly less potent than estradiol.
Conjugated estrogens may be adminis-
tered orally or parenterally. The usual dose
for menopausal symptoms, orally, is 625
pg to 1.25 mg, daily, cyclically, and a pro-
gestin may be added concurrently or se-
quentially.

PRESCRIPTION PRODUCT. Premarin®.

The designation esterified estrogens also
refers to a mixture of the sodium salts of
the sulfate esters of the estrogenic sub-
stances that are of the type excreted by
pregnant mares. 1 his mixture differs from

184

STEROIDS

conjugated estrogens because it has more
estrone and less equilin metabolites. It
must contain not less than 75% and not
more than 85% of sodium estrone sulfate
and not less than 6.5% and not more than
15% of sodium equilin sulfate. It is used
orally for the same purposes and in the
same dosage range as are preparations of
conjugated estrogens. *

PRESCRIPTION PRODUCT. Menest®.

A number of stilbene derivatives, as well
as various other compounds, have estro-
genic activity. These synthetic substances
are active orally and have been used in
some instances as therapeutic substitutes
or the estrogenic steroids. These stilbene
! erivatives are absorbed rapidly, de-
coyed slowly, and active for a prolonged
nod. However, the side effects of nausea
id vomiting also tend to be enhanced,
•iethylstilbestrol is probably the best
nown of these substances, but other use-
ul derivatives include chlorotrianisene
face®) and dienestrol.

Diethylstilbestrol

Corpus Luteum — Progestin. The corpus lu-
j um is essential to the maintenance of
uman pregnancy during the first half of
he term. Its principal hormonal functions
ire:

1 . Preparation of the uterine mucosa to
receive the fertilized ovum.

2. Development of the maternal pla-
centa.

3. Continuation of the development of
the mammary glands in preparation
for lactogenic action of anterior pitui-
tary.

4. Suppression of ovulation for the du-
ration of pregnancy.

5. Antagonism of the stimulating effect
of estrogens on the uterine muscle to
produce a relaxation of the uterus.

The active hormone of the corpus luteum

is progesterone. It can be prepared syn-
thetically from a number of steroidal sub-
stances. Progesterone is relatively inactive
on oral administration, and it is given buc-
cally or parenteraliy. This hormone is used
in the treatment of amenorrhea,
dysmenorrhea, endometriosis, functional
uterine bleeding, premenstrual tension,
and threatened or habitual abortion.

Progesterone. Progesterone is pregn-4-
ene-3,20-dione. The usual dose, intramus-
cularly, is 50 to 100 mg for one dose oniy,
or 5 to 10 mg a day for 6 days for functional
uterine bleeding.

PRESCRIPTION PRODUCTS. Femotrone in
Oil® and Progestaject®.

A number of synthetic progestins have
been developed that have such advantages
over progesterone as fewer side effects
when administered over prolonged pe-
riods, oral efficacy, and greater potency.
Such compounds as hydroxyprogesterone
caproate in oil (Delalutin®), methoxypro-
gesterone acetate (Provera®), and noreth-
indrone (Norlutin®) may be used as ther-
apeutic substitutes for the natural
hormone.

One of the normal physiologic functions
of progesterone is to suppress ovulation
during pregnancy. This hormone is not
formed during the first half of a normal
menstrual cycle, but administration of it or
of some other progestational agent during
this part of the menstrual period offers an
effective means of birth control. When pro-
gestins are used as oral contraceptives,
some estrogenic substance is frequently
added, either by combined formulation or
sequential administration, to the therapeu-
tic approach to reduce side effects.

CH 3

C-0

STEROIDS

185

Progesterone is also available in an in-
trauterine device (1UD). The hormone is
dissolved in silicone oil, and the flexible
polymer of the IUD acts as a membrane to
allow for the slow release of progesterone
(65 jxg daily) into the uterine cavity. The
IUD contains enough progesterone to last
1 year, and the failure rate is about. 2%.
The failure rate of the same device without
progesterone is approximately 18%. The
product is called Progestasert®.

READING REFERENCES

IUPAC-IUB Revised Tentative Rules for Nomencla-
ture of Steroids, J. Org. Chem., 34(6):1517, 1969.

Beher, W.T.: Bile Acids. In Monographs on Atheroscle-
rosis, Vol. VI, Kritchevsky, D., Pollack, O.J., and
Simms, H.S., eds., Basel, S. Karger AG, 1976.

Bodem, G., and Dengler, H. J , eds.: Cardiac Glycosides,
Berlin, Springer-Verlag, 1978.

Charney, W., and Herzog, H.L.: Microbial Transfor-
mations of Steroids, New York, Academic Press,
Inc., 1967.

Deuce, J.B.: Steroids and Peptides, New York, John
Wiley & Sons, Inc., 1980.

Goodwin, T.W.: Biosynthesis of Plant Sterols and
Other Triterpenoids, In Biosynthesis of Isoprenoid
Compounds, Vol. 1, Porter, J.W., and Spurgeon,

S.L., eds., New York, John Wiley & Sons, Inc.,
1981.

Gower, D.B.: Steroid Hormones, Chicago, Year Book
Medical Publishers, Inc., 1979.

Greeff, R., ed.: Cardiac Glycosides, Parts I and II, Berlin,
Springer-Verlag, 1981.

Iizuka, H., and Naito, A.: Microbial Transformation of
Steroids and Alkaloids, State College, Pennsylvania,

1 _ University Park Press, 1967.

Lehmann, F.P.A., Bolivar, G.A., and Quintero, R.R.:
Russell E. Marker, Pioneer of the Mexican Steroid
Industry, J. Chem. Educ., 50(3):195, 1973.

Makin, H.L.J., ed.: Biochemistry of Steroid Hormones,
Oxford, Blackwell Scientific Publications, 1975.

Nair, P.P., and Kritchevsky, D., eds.: The Bile Acids;
Chemistry, Physiology, and Metabolism, Vols. I and
II, New York, Plenum Press, 1971, 1973.

Nes, W.R., and McKean, M.L.: Biochemistry of Steroids
and Other Isopentenoids, Baltimore, University Park
Press, 1977.

Pasqualini, J.R., ed.: Receptors and Mechanism of Actum
of Steroid Hormones, Parts I and II, New York, Mar-
cel Dekker, Inc., 1976, 1977.

Sanders, H.J.: Arthritis Drugs, Chem. Eng. News,
Aug. 12, 46, 1968.

Schulster, D.. Burstein, S., and Cooke, B.A .-.Molecular
Endocrinology of the Steroid Hormones, London,
John Wiley & Sons, Ltd., 1976.

Thomas, J. A., and Singhal, R.L., eds. : Molecular Mech-
anisms of Gonadal Hormone Action, Baltimore, Uni-
versity Park Press, 1975.

Wilkerson, R.D.: Cardiac Pharmacology, New York, Ac-
ademic Press, Inc., 1981.

Witzmann, R.F.: Steroids. Keys to Life, New York, Van
Nostrand Reinhold Co., 1981.